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'(No Model.) I

J. 0. MARTINM APPARATUS FOR DRYING WHITE LEAD. No. 286,721.. 'Patented- Oct. 16 1883.

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UNITE STATES PATENT OFFICE.

JOHN G. MARTIN, OF RICHMOND, COUNTY or SURREY, ENGLAND.

APPARATUS FOR DRYING WHITE LEAD.

SPECIFICATION forming part of Letters Patent No. 286,721, dated October 16, 1883.'

in Germany January 28, 1879, No. 7,051; in Belgium March 18, 1879, No. 47,688, and in Austria June 5, 1880.

ToaZZ whom it may concern.-

Be it known that I, JOHN COWDERY 1\IAR- TIN, a subject of the Queen of Great Britain, and residing at'Richmond, in the county of Surrey and Kingdom of Great Britain, have -invented certain new and useful Improved Machinery for Drying WVhi-te Lead and other Materials, (for which I have obtained Letters Patent in Great Britain, dated July 25, 1878, No. 2,958; in France, dated January 27,1879, No. 128, 670 in Belgium, dated March 18, 1879,

No. 47,688; in Germany, dated January 28,

1879, No. 7 ,051; and in Austria, dated June 5, 1880;) and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters or figures of reference marked thereon, which form a part of this specification.

The improvements consist, first, in spreading white lead or other materials in a similar pulpy condition upon a moving endless absorbent cloth or series of cloths, covered by a second endless cloth or series of cloths, and passing the one over and between and the other under and between several heated cylinders, also covered with cloth, and so arranged that the surface of the endless cloths in contact with the material to be dried shall not greatly deviate from a horizontal position in passing from one cylinder to another; secondly, when the materials are so far dry as to become parti ally powdered or granular in completing the drying by causing the said'materials to enter the upper part of a machine, consisting of a casing heated by steam, the section across which is in the form of the letter U, open at the top, and having within it a revolving cylinder, also heated by steam, and carrying on its external surface several projections, some placed parallel with the axis to carry the material round, and some placed at an angle to the axis, in order to thrust the material forward longitudinally; or such projections may be arranged spirally round the exterior of the revolving cylinder in the manner of screwthreads, placed at such an angle with the axis of the cylinder as to cause the 1naterial,which is fed upon one end thereof, to be carried round within the casing as the cylinder revolves, and also to be thrust forward and delivered at. the opposite end of the machine to that at which it entered.

Other matters and things in a granular or powdered condition, whether subjected pre viously to the operations comprising the first part of this invention or not, may be dried by Application filed July 12, 1882. (No model.) Patented in England July 25, 1878, No. 2,958; in France January 27, 1879, No. 128,670

the machine described in the second part of this invention.

In the drawings, Figure 1 shows an arrangement for using two endless absorbent cloths, f f, in accordance with the first part of my invention, the whole of the heated revolving cylinders a a, excepting one at each end of the machine, being, by preference, covered with absorbent cloth, tightly fitted over them, and which (by close contact with the endless cloths ff, between which the material k in process of drying is carried over and under them) absorb moisture from the material and become dry as the cylinders revolve. Sometimes, to facilitate the absorption, I press the cloths f f, containing between them the material to be dried, against the cylinders a c by means of pressurerollers b I), placed alternately above and below each endless cloth and between the heated cylinders a a, the upper rollers, b b, pressing downward on the cloth by their own weight, and the lower rollers, b I), being caused to pres s upward by means of levers, springs, or other suitable means, each roller being caused to revolve merely by contact with the moving cloths and cylinders. The drying-cylinders a a are arranged so that the lowest parts of the peripheries of the upper series, under which the endless cloths f f pass, shall not be more than a few inches below the highest parts'of the peripheries of the lower cylinders, in order that the angle formed by the cloth in rising or descending from one cylinder to another may be so slight as to allow the material between the cloths to pass forward without falling back.

Fig. 2 shows an arrangement by which the cloths with the material in process of drying may be maintained in a perfectly horizontal position, and also that, instead of covering each cylinder separately with absorbent cloth, an

endless absorbent cloth, 9 or 9, may be passed round them and caused to work within each of the two outer cloths. Sometimes when using this arrangement I do not heat the cylindersmarked c c at the feeding end of the ma chine which are in contact with the parts of the cloths next the material in process of drying. The lower endless cloths, ff, are extended, as shown at Figs. 1, 2, and 3, form ing a fiat surface or table, supported'by means of small rollers f f, or in any other convenient manner, and the material to be dried is thinly spread upon this fiat moving surface by passing it from the hopper it between the pair of rollers d and d, which extend across the width of the machine, and to which rollers the material adheres and is carried round and removed by a narrow scraper, c, fixed against the lower part of the feed-roll d, whence it falls onto the cloth beneath and is carried between the drying-cylinders an in Figs. 1 and 3, or c c in Fig. 2, the first pair of which in Fig. 1 and the several pairs of cylinders marked c in Fig. 2 are placed sufficiently close together to exert pressure upon and further spread it.

Fig. 3 shows an enlarged section of the feedrolls with the position of scraper and cloth beneath.

Similar letters refer to like parts in all the figures.

\Vhen steam is used for heating the revolving cylinders, they are fitted with the means usually employed in cylinder dryinganachines for discharging the condensed water and preventing the escape of the steam, and the various moving parts of the machine are driven by the usual gearing, or in any other convenient manner.

I have found that the cloths in passing be tween the cylinders a a, I) I), and c 0 (see Figs. 1, 2, and 3) sometimes become creased, and do not run evenly. I correct this and keep them fiat on returning to the feed end of the machine by means of two pairs of small rollers or wheels, B B, (see Figs. 4 and 5,) working at an angle with the direction in which the cloths are traveling, and placed at opposite edges of each of the moving cloths, such wheels being cut away or flattened at one or more parts, B B, of'theii."

circumferences, and so arranged that the said flat parts of each pair work opposite each other as they revolve, and the cloth is thereby a1- ternately stretched by the round parts and released as the fiat parts come opposite each other. By this means the pair of rolls on one edge of the cloth pulls against the pair on the opposite edge, thereby extending the cloth and removing the creases. These rollers may be geared together, as shown in Fig. 4, so as to revolve synchronously.

If preferred, other means may be employed for removing the creases from the cloths.

The drying-cylinders c and c, Fig. 2, may be either covered with absorbent cloth or felt, tightly fitted over them, or covered by a second endless cloth working within the outer one, carrying the material to be dried, as hereinbefore described; or the drying may be effected, although less rapidly, by using the outer cloths only, the cylinders being not otherwise covered with cloth.

WVhen the machine, as above described. is from thirty to thirty-five 'feet long, and is driven at a speed such that the material occupies from forty-five to sixty minutes in passingbetween the cylinders, the moisture is readily extracted to within from three to five per cent, and if the length of the machine is sufficiently extended, this may be entirely removed; but to avoid using excessively long machines, I prefer to finish the drying by passing the material over the surface of a sufficiently strong 7 drying-cylinder, I), (see Figs. 6 and 7,) heated by steam or otherwise, and fitted with the usual means for removing condensed water, and working within a steam or otherwise heated casing, a a.

The cylinder I) is fitted with proj ecting strips or screw-threads e 6, preferably of metal, the angle of which may vary according .to the description of material intended to be dried and the speed at which the machine is driven. I have found the angle formed by a turn of from a quarter to half the circumference of the cylinder in alength of five diameters to give good results; but, any other form ordescription of projections that will carry the material round the cylinder as well as thrust it forward may be used.

The first part of my invention, although especially applicable to the drying of white lead, is also applicable, more or less, to the drying of all substances or materials from which moisture can be extracted by absorption. The second part of my invention is also applicable, more or less, to the drying of all substances in a granular or powdery condition.

Instead of heating boththc cylinder and the casing, the cylinder only, or the casing only, may be heated.

Although I have described endless absorbent cloths, I do not confine myself to them, as it will be evident that similar effects may be produced by employing cloths of definite lengths and causing them to travel alternately forward and backward, the feeding apparatus being arranged accordingly; and instead of passing the absorbent cloths over cylindrical heated surfaces, they may be caused to pass over heated surfaces of other form.

I claim- 1. The combination of the absorbent cloths ff with the heated cylinders a a, whereby the said absorbent cloths f f are operated with the material to be dried between them, substantially as hereinbefore described, and illustrated in Figs. 1, 2, and 3 of the drawings, and for the purpose set forth.

2. The cylinders a a, covered with separate absorbent cloths, or, in the alternative, the cylinders c 0, provided with endless coverings of absorbent cloth 9 g, each adapted to sev- IOC eral such cylinders and working Within the outer absorbent cloths, f f, as hereinbefore described, and illustrated in Figs. 1 and2 of the drawings, and for the purpose set forth.

3. The combination of the cylinder I), having external projections or screw-threads, c, with an external casing, a, either or both of which may be heated, substantially as hereinbefore described, and illustrated in Figs. 6 and 7 of the drawings, and for the purpose set forth.

4. The tension rollers or wheels B B, 'constructed with flat or straight portions B B, 

